1. Field of the Invention
The present invention relates to systems and methods for checking the validity of electronic data transmission, and particularly to a system and method for checking the validity of data transmission through a network according to a checksum mechanism.
2. Prior art of the invention
In any communication system, it is desirable to detect data transmission errors. Each packet transmitted across a communications network between nodes contain data and a header that describes the data. In a typical communications system utilizing Internet Protocol (IP), a sending computer or node transmits the header and the data to one or more receiving computers or nodes. The header contains a checksum and other components. The checksum generated by the sending node is for examining the data, and the receiving node uses it to determine whether any errors were introduced into the data during transmission. In order to generate the header, the sending node must read all the data. This usually requires the sending node to examine every byte of the data twice, once to generate the checksum and again to transmit the data.
Presently, a checksum mechanism is usually used to check whether the data have been interfered with during the data transmission. For example, the transmission communication protocol (TCP) uses a checksum to protect the data which is transmitted. This checksum is located in the TCP header of the Internet datagram packet. As described above, all of the data must be examined before the data can begin to be transmitted. This results in two adverse consequences. First, all of the bytes of data must be read twice, once to generate the checksum, and again to transmit the data. This cuts down the maximum throughput possible for this protocol. Second, the beginning of the data cannot be transmitted until the end of the data is known. This adds to the latency of transmission.
U.S. Pat. No. 5,815,516 issued on Sep. 29, 1998 and entitled “Method And Apparatus For Producing Transmission Control Protocol Checksums Using Internet Protocol Fragmentation” discloses a method and apparatus for producing transmission control protocol (TCP) checksums using IP fragmentation. The TCP uses a checksum to protect the data which is transmitted. This checksum is located in the TCP header of the Internet datagram packet. In the disclosed method, a TCP module receives a data packet to be transmitted, and prepares a first IP data fragment without a checksum for the received data packet. The first IP data fragment is transmitted. During the transmission of the first IP data fragment, a checksum is generated. Then an IP header fragment including the generated checksum is transmitted.
However, there is nothing known in the art which can check error data generated when data bits exchange places; that is, when data in two or more data bytes is out of order. This can occur when the data transmission through the network is interfered with in some way. The above-mentioned solutions cannot reliably check for such error data. A system and method for checking the validity of data transmission which can overcome the above-mentioned problem is desired.